Exergy and energy analysis of a ground-source heat pump for domestic water heating under simulated occupancy conditions

• Exergy and energy analysis of a ground source heat pump for water heating is given.
• Hot water use protocol is based on an established benchmark.
• The benchmark captures the living habits of the average American household.
• Sources of systemic inefficiencies, the main cause of waster energy are identified.
• Understanding performance metrics is vital for judicious use of renewable energy.

This paper presents analysis of a 5.275 kW (1.5-ton) water-to-water ground source heat pump (WW-GSHP) satisfying hot water needs in a 345 m2 research house operated under simulated occupancy conditions. The hot water use protocol from the Building America Research Benchmark Definition claims to capture the living habits of the average American household and its impact on energy consumption.Energy and exergy analyses provide insight on system efficiency and sources of irreversibility, the main cause of wasted energy. The WW-GSHP shared the ground loop with a 7.56 kW water to air ground source heat pump (WA-GSHP) to space condition the same house. Understanding the performance of GSHPs is vital if the ground is to be used as a viable renewable energy resource.